Wall nucleation propagation for racetrack memory

Abstract

A shift register is provided, the shift register comprising at least one track including a storage region. The storage region comprises a plurality of magnetic domains for storing data. A given first one of the plurality of magnetic domains is adjacent to a given second one of the plurality of magnetic domains. The given first one of the plurality of magnetic domains and the given second one of the plurality of magnetic domains are arranged in a linear configuration. Further, the given first one of the plurality of magnetic domains and the given second one of the plurality of magnetic domains are separated from one another by at least one layer of non-magnetic material. The at least one layer of non-magnetic material preventing a propagation of a nucleated wall from traveling between the given first one of the plurality of magnetic domains and the given second one of the plurality of magnetic domains. The shift register is configured such that an electric current applied to the track is operative to shift data stored within at least one of the plurality of magnetic domains of the storage region, along the track, in a direction of the electric current. The data stored within the at least one of the plurality of magnetic domains is shifted as a function of the direction of the electric current.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to electrical and electronic devices and systems, and more particularly, to semiconductor memory.BACKGROUND OF THE INVENTION[0002]New shiftable magnetic shift registers, more commonly known as racetrack memory, may be a solution for our growing need for faster and cheaper high capacity memory. Racetrack memory could become a viable alternative to current forms of data storage. For instance, mechanical disk drives provide high capacity storage at a low cost, but mechanical drives are fundamentally unreliable due to their many moving parts. Solid state drives provide relatively reliable storage, but at a high cost for low capacity. Racetrack memory should allow high capacity storage at a fraction of the cost of solid state memory. However, additional improvements would make racetrack memory a more cost-effective and reliable alternative.[0003]The general design of racetrack memory has been documented. See, e.g., U.S. ...

AI Technical Summary

Benefits of technology

The present invention provides a shift register with controlled wall nucleation, wall propagation, and wall annihilation during a shift cycle. This is achieved by promoting a shift in the magnetic domain configuration within a given magnetic domain, preventing a propagation of a nucleated wall from traveling between adjacent magnetic domains. The shift register includes a storage region with a plurality of magnetic domains for storing data, and an electric current applied to the track is operative to shift data stored within the magnetic domains. The data is shifted as a function of the direction of the electric current. The invention also provides a method of shifting data in a shift register and a shift register with at least one portion of weak magnetic material to encourage wall nucleation and destroy the wall with a layer of non-magnetic material.

Problems solved by technology

For instance, mechanical disk drives provide high capacity storage at a low cost, but mechanical drives are fundamentally unreliable due to their many moving parts.

Solid state drives provide relatively reliable storage, but at a high cost for low capacity.

Further, the amount of time during which the electric current is applied also affects the movement of the domains along the track.

However, one issue with conventional racetrack memory designs is maintaining consistent domain movements.

Further, even if no current is applied, the domains may move in the rest state, modifying the stored data and resulting in erroneous data reads.

To a limited extent, pinning does yield more consistent domain movements; however, pinning does not fully address spontaneous drifting of the domains along the magnetic track.

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